In ancient times how did they prevent people from misrepresenting themselves (e.g. "Hello, I am the king of Someplace You Never Heard Of") and commiting fraud?

Factual Questions
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And even earlier in Douglas Fairbanks’ 1924 Thief of Bagdad

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Also the original fairytale of Puss in Boots. No genie, but a hyper-competent cat.